Sequence-specific 1H NMR assignments and secondary structure of porcine motilin.
Sequence-specific 1H NMR assignments and secondary structure of porcine motilin.
复制标题
猪胃动素的序列特异性 1H NMR 归属和二级结构。
DOI：
10.1021/bi00476a015
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Shriver,J
中科院分区：
文献类型：
--
作者：
Khan,N;Graslund,A;Ehrenberg,A;Shriver,J
摘要：用圆二色性和二维核磁共振氢谱研究了22个残基的肽激素胃动素的溶液结构。圆二色性光谱表明在水溶液中存在α-螺旋二级结构，并且该二级结构可以用六氟-2-丙醇稳定。用二维核磁共振技术对猪胃动素在30%六氟异丙醇中的质子核磁共振谱进行了序列特异性归属。所有的骨干质子共振（NH和aCH）和大部分的侧链共振已被分配使用双量子滤波COSY，RELAYED-COSY，和NOESY实验。模拟NOESY交叉峰强度作为混合时间的函数表明，自旋扩散对胃动素大小的肽的影响相对较小，从而允许使用长混合时间来自信地进行分配和描绘二级结构。连续的aCH-NH和NH-NH NOESY连接性在肽的长度的显著部分上观察到。许多中等范围的NOESY交叉峰表明肽从Glu 9折叠成α-螺旋至Lys 20，这与CD测量确定的50%螺旋含量一致。所选NOESY交叉峰相对于相应对角峰的强度用于估计肽的旋转相关时间约为2.5 ns，表明肽在本文所用条件下以单体形式存在于溶液中。
Revised Manuscript Received February 28, 1990 abstract: The solution structure of the 22-residue peptide hormone motilin has been studied by circular dichroism and two-dimensional'H nuclear magnetic resonance spectroscopy. Circular dichroism spectra indicate the presence of a-helical secondary structure in aqueous solution, and the secondary structure can be stabilized with hexafluoro-2-propanol. Sequence-specific assignments of the proton NMR spectrum of porcine motilin in 30% hexafluoro-2-propanol havebeen madeby using two-dimensional NMR techniques. All backbone proton resonances(NH and aCH) and most of the side-chain resonances have been assigned by using double-quantum-filtered COSY, RELAYED-COSY, and NOESY experiments. Simulations of NOESY cross-peak intensities as a function of mixing time indicate that spin diffusion has a relatively small effect in peptides the size of motilin, thereby allowing the use of long mixing timesto confidently make assignments and delineate secondary structure. Sequential aCH-NH and NH-NH NOESY connectivities were observed over a significant portion of the length of thepeptide. A number of medium-range NOESY cross-peaks indicate that the peptide is folded into a-helix from Glu9 to Lys20, which agrees favorably with the 50% helical content determined from CD measurements. The intensities of selected NOESY cross-peaks relative to corresponding diagonal peaks were used toestimate a rotational correlation time of approximately 2.5 ns for the peptide, indicating that the peptide exists as a monomer in solution under the conditions used here.